Polycationic bimetallic oxide CoGa2O4 with spinel structure: dominated pseudocapacitance, dual-energy storage mechanism, and Li-ion hybrid supercapacitor application

In this work, the polycationic bimetallic oxide CoGa2O4 with spinel structure was successfully prepared by simple hydrothermal and subsequent calcination methods. Following, half-cell electrochemical test showed that this material presented a hybrid energy storage mechanism, namely combining Ga alloying and Co3O4 conversion. The combination of the two energy story mechanisms makes CoGa2O4 have higher conductivity than other single metal oxides. According to the calculation of the relationship between peak current and sweep speed, the b = 0.93 of CoGa2O4 is obtained, and its electrochemical behavior is closer to capacitive behavior than that of Co3O4 and NiCo2O4. This makes it have excellent rate performance and cycle stability. Consequently, the CoGa2O4//AC Li-ion hybrid supercapacitor (LIHSC) device exhibits excellent cycling stability (capacity retention of 83% after 8000 cycles), high-energy density of 111.5 Wh kg(-1) (at 100 W kg(-1)), and high power density of 3927 W kg(-1) (at 24 Wh kg(-1)).